The nature of thé sea-ice extent in Hudson Bay, Baffin Bay and thé Labrador Sea associated with thé three strong simultaneous NAO (North Atlantic Oscillation) and ENSO (El Nino-Southern Oscillation) épisodes of 1972/73, 1982/83 and 1991/92
RÉSUMÉ On examine la nature et l'étendue de la glace de mer sur la baie d'Hudson, la baie de Baffin et la mer du Labrador, associée à trois forts épisodes simultanés de la NAO (Oscillation Nord-Atlantique) et de l'ENSO (El Nino-Oscillations australes) en 1972 -73, 1982 -83 et 1991 -92. Durant le premier épisode, 1972
Introduction Wang et al. (1994a) recently performed a comprehensive data study of thé interannual variability of sea-ice cover in Hudson Bay, Baffin Bay and thé Labrador Sea for thé period 1953-88. In this study, they also explored thé relationship of thé seaice variability to thé Southern Oscillation (SO) and thé North Atlantic Oscillation (NAO), two well-known atmospheric climatic fluctuations in thé tropical Pacific and North Atlantic, respectively. In particular, they used thé composite data analysis method together with thé spatial student t-test to show that during thé Low/Wet (El Nino) phase of thé SO (van Loon and Madden, 1981) or thé stro:ig westerly phase (deepened Icelandic Low in winter) of thé NAO (Rogers, 1984), positive sea-ice area anomalies (as determined from sea-ice concentration data) generally occurred in thé study région. During thé 1953-88 period studied by Wang et al. there were two coincident strong ENSO and NAO épisodes: 1972/73 and 1982/83. However, thé sea-ice and atmospheric data for thèse two spécial cases were only briefly examined in Wang et al.The main purpose of this paper is to présent a case study of thé behaviour of thé sea-ice cover and overlying atmosphère in Hudson Bay and thé Baffin Bc y-Labrador Sea région during thé aforementioned two épisodes (1972/73 and 1982/83), as well as during thé récent joint ENSO-NAO event of 1991/92. More specifically, descriptions of thé spatial and temporal changes of thé sea-ice extent will be given in conjunction with thé updated (1953-93) sea-level pressure (SLP) and surface air température (SAT) variations. A brief discussion of sea surface température (SST) anomalies in thé northwestern North Atlantic during thé three case-study periods will also be provided.In an earlier study, Rogers (1984) examined thé possible association between thé NAO and thé SO in thé northern hémisphère using winter SLP and 500 mb height data. He found that only over thé western Atlantic did large pressure and height variations occur in thé extrêmes of both oscillations. We will show that this resuit is consistent with thé findings of thé présent study which uses updated data.